kyle!

So I got this '84 Schwinn Super Sport. When I'm in a gear that requires any sort of torque I get this knocking sound from the drive train. The cranks are Sugino AS, the freewheel is a Suntour 6 speed.

I've had the bottom bracket replaced with a modern cartridge one and also replaced the chainring bolts. Lastly, the cranks are not loose.



I'm not sure where to look at next. Could it be something from the freewheel? Or just the chain?


Thanks.

greyghost_6

Yes, it may be the freewheel. Sometimes they have a slight wobble. Does it knock when you coast?

kyle!

No, I searched older posts and found someone with the same problem.

https://bikeforums.net/showthread.php...ranks+knocking

It must be something in the wheel. The cassette does wobble very little but it doesn't knock at all when I coast.

I rode it more tonight and found it's only knocking when I'm in the small ring(42t) and a smaller cog in the back so I suppose it could be a slight cross chain issue.

Oh boy these old bikes are a pain. But they look so nice you just want to make them work.

Torchy McFlux

Try replacing the pedals with some that you know are OK and see what happens.

Sanchana

I would bet the f/w

nick burns

What's the pattern of the knocking? Once per pedal revolution, per chain length, or random? It might help identify the source.

The first place I would start looking is the pedals and bottom bracket. Was the knocking present before you replaced the BB?

Here's Sheldon's link on noises:

https://www.sheldonbrown.com/creaks.html

Philatio

Yep that was me. I isolated the problem to the wheel, and finally just bought a new wheel with a cassette hub. fwiw, replacing the wheel and no other components "fixed" the problem. I thought I had mentioned it in my thread, but my knocking only sounded in certain gears as well.

I tore down the wheel, lubed all spoke crossings, lubed at the nipples, and lubed the spokes at the hub interface. It seems possible it was because of a crack in the hub, which only was stressed just right in certain gears. However I wasn't able to ever find any.

I'm going to try to use that same wheel for a FG suicide conversion - I guess I'm hoping that since my noise never sounded while I was in the closest gear to the hub, it's reasonably likely I can get away with the single cog in the same position.

kyle!

Crack in the hub. Weak.

To Mr. Burns, the knocking it about the same rhythm as the chainring bolts, but I replaced those and the holes aren't ovalized.

Also, the pedals are legit.

The more I read it sounds like Philatio had the same exact problem.

kyle!

So.


It's definitely the back wheel. I put my girlfriend's rear wheel on and no noise to speak of. I'm going to take it to the shop soon.


In the meantime, is it hard to get a newer rear wheel built up or find a suitable wheel for this frame? The current hubs are Sunshine. I'm not sure of the exact spacing. It seems like they're on the narrower side. This is of course if there is something wrong with the hub, not just the freewheel.

Sorry to seem so clueless but I've been more into fixed gear bikes up until now so I have a lot to learn.

DMF 

It could be that your wheel bearings aren't correctly adjusted. See what the shop says before planning more drastic action.

kyle!

So, they took the freewheel off. Everything looked fine. They greased it up, put it back on and then "oh look at this spoke, it's not crossed with any other spokes".

Apparently someone replaced a spoke on the back wheel and just kinda slapped it on there without really building it into the existing pattern. So, I'm gonna go back Sunday and they're gonna replace the spoke and hopefully get rid of the knocking.



Hopefully.

Philatio

I've got a couple doubts with that being the cause.

1) shouldn't it have been knocking since the offending spoke was laced in? what could have caused it to start?

2) assuming our problem is the same one, all of my spokes are correctly crossed.

But please keep this thread updated, I would very much like to track this down.

kyle!

I will certainly keep you up on this. As far as a cracked hub or maladjusted bearings, the guy at the shop said they both look fine and spin perfectly. But the part that was lame was he took it out for two short rides and heard nothing.

Then I felt crazy. But he's being awesome about so, Sunday. The spoke will be replaced. If that doesn't help. Beyond re-lacing the wheel I'll be done and maybe just look for a new wheel.

Speaking of a new wheel. I believe my rear spacing is something like 120mm or 126mm. I've yet to actually measure it. Is your around the same? Did you end up finding a new wheel?

Philatio

Doh! gotta hate that

My bad wheel was spaced at 126 with a 6 speed freewheel. I bought a 7 speed wheel with a cassette that seems to be spaced the same. I bought my wheel replacement through ebay for about $30 (but then got boned with $30 shipping on top) but it was still a pretty reasonable price.

Of course then I had to replace the shifters too, as well as buy a cassette for the wheel (the ad didn't mention it was severely worn). But all in all it was probably close to $100 total for the switch.

Philatio

Just to update this from my side...

I completed converting my wheel to a suicide fixed gear, and it rides fine with no knocking whatsoever. So I think that means that everything has been eliminated as a possible suspect.

kyle!

Oh wow. I had forgotten I made this thread. I haven't gotten my bad spoke replaced yet. I've kind of just tried to ignore the noise.

I'm looking at some different old wheelsets too.

I'm still gonna try to get my current wheel situated though, I'll post with any progress.